1. Field of the Invention
Subject invention is related to signal processing and more particularly to an adaptive filter for cancelling noise without affecting the signal and thereby increasing the signal-to-noise ratio.
2. Description of the Prior Art
There are many occasions when a microphone is required to pick up sound from a talker or loudspeaker situated to the right of the microphone, while simultaneously there is intense noise radiating from a noise source to the left of the microphone. Noise-cancelling or noise-reducing devices based on transmission loss, such as, for example, sound absorbers placed between the microphone and the noisy wall enclosing a machine shop, provide one method of reducing the noise (acoustically) before it is picked up by the microphone. However, the sound-absorbing material often occupies a large volume, and when the signal bandwidth is extended to include the low end of the audio bandwidth, this volume can be unacceptably large.
An alternate and more desirable method is to use an electronic noise-cancelling or noise-reducing system to reduce the transduced noise (now in electrical form) after the microphone has picked it up.